Scratch 1.4 File Format
The Scratch 1.4 File Format saves projects in version 1.4 of the Scratch programming language, a language designed to teach programming to young children. Since the program code consists of graphical tiles rather than text-based source code, a binary format was used to save it, along with the associated objects which form part of a program project.
Scratch projects are stored in files with a .sb extension. They start with a 10-byte header containing the ASCII characters ScratchV02. Multi-byte numeric values within the file are stored in big-endian fashion.
A sprite file, with the extension .sprite, stores a sprite along with related variables and lists, in a format similar to the project file but without the header at the start.
Detailed documentation can be found in the Scratch wiki.